Clay minerals contain structural and molecular water, a key element that allows us to recognise and characterise them on Mars by remote sensing.
Clays are detected on Mars by spacecraft in orbit that peer down at the surface using infrared cameras. The NASA rover Curiosity is also in search of clays, and has unexpectedly found some at an early stage in its mission.
Most of the clays detected on Mars are relatively rich in iron and magnesium, because they formed from aqueous alteration of basaltic rocks, which are also rich in those elements.
This family of clays displays significant variation in structure and chemistry. In fact, individual clay minerals can be inter-layered with each other at the scale of nanometres.
Because they are so fine-grained and chemically complex, clays are notoriously difficult to study – which is why there are still many discoveries waiting on the horizon.
Submarine hydrothermal sites on Earth are known for their black smokers - jets of super-heated fluids loaded with metals. Clays forming in these environments are similar to ancient Martian clays.
Dr Javier Cuadros
Economic and Environmental Earth Sciences Division
Natural History Museum
+44 (0)20 7942 5543
The Hydro-Mars project is funded by the European Commission, as an Intra-European Marie Curie Fellowship.